The Wolves and Moose on Isle Royal. Isle Royale images from: .
Transcript of The Wolves and Moose on Isle Royal. Isle Royale images from: .
The Wolves and Moose on Isle Royal
Isle Royale images from: http://www.kgcphoto.com/isle_royale_national_park.htm
Wolf and moose images from http://blog.kingsoutdoorworld.com/2007/02/
alright – back to work…
• Largest island in lake Superior• Isolated from mainland most of the time• Home to moose and wolves
For now: • concentrate on actions between wolves and
moose herd• ignore other influences on moose population
(such as ?)• rather limited “systems” approach
(see additional reading on web page)
How to describe feedback:
size of moose herd size of wolf pack
size of wolf pack size of moose herd
positive feedback
negative feedback
more food on four legs
more hungry mouths to feed
Example of a Feedback Loop
Size of moose herdMore food for wolves
Appetite for moose Size of wolf pack
Note:
A feedback loop needs to be closed !
Therefore it needs at least
• two components
• two connections between these components
Or Somewhat Simplified:
size of moose herd size of wolf pack
positive
negative
How to analyze a feedback loop:
• Need to disturb the system• Doesn’t matter where you start• Analyze how disturbance moves through
the system
• How does wolf – moose system behave ?
size of moose herd size of wolf pack
Sign of Feedback Loop
• number of negative couplings determines sign of feedback loop
• even number of negative couplings: positive feedback loop
• odd number of negative couplings: negative feedback loop
Effects of Negative of Positive Feedbacks
Effects of Negative of Positive Feedbacks• positive feedback: input signal will be
amplified
• negative feedback: input signal will be damped
Size of wolf and deer herds
From Science Times (3/19/1996) (http://www.admin.mtu.edu/urel/PressReleases/feature/wolves/wolf.html)